For visible light image, set infrared-visible to 100. For infrared light image, set infrared-visible to 0. Combine both by setting infrared-visible to around 50. Humans can't see infrared with the naked eye.
Infrared image of cosmic cloud BHR 71 from NASA's Spitzer Space Telescope. Two young stars, in a cosmic cloud called BHR 71, are destroying their natal dust cloud with jets of radiation. In visible light (infrared-visible set to 100), BHR 71 is a large black structure. The yellow light toward the bottom of the cloud is the only indication that stars might be forming inside. In infrared light (infrared-visible set to far left, at 0), the baby stars are shown as the bright yellow smudges toward the center. Both of these yellow spots have wisps of green shooting out of them. The green wisps reveal the beginning of a jet. Like a rainbow, the jet begins as green, then transitions to orange, and red toward the end. Humans can't naturally see infrared. The combined visible-light and infrared composite (infrared-visible = 50) shows that a young star's powerful jet is responsible for the rupture at the bottom of the dense cloud in the visible-light image. Astronomers know this because burst of light in the visible-light image overlaps exactly with a jet spouting-out of the left star, in the infrared image. The infrared image is made up of data from NASA's Spitzer's infrared array camera. Blue shows infrared light at 3.6 microns, green is light at 4.5 microns, and red is light at 8.0 microns.
